The present invention relates to a post-mix beverage dispensing valve for dispensing concentrate (such as syrup) and diluent (such as soda water) in controlled volumetric proportions. More specifically, the present invention relates to an apparatus and method for injecting metered quantities of syrup or concentrate into measured quantities of diluent flowing through a diluent supply conduit.
Post-mix beverage dispensing valves typically dispense syrup and a diluent such as carbonated water (soda) simultaneously through a mixing nozzle into a beverage cup. To obtain the proper mixture ratio, current valves control the flow rate of the syrup and soda often with the use of manually-adjustable flow controls. These flow controls do not always achieve a proper mixture ratio because: a change in flow rate in one fluid does not cause a corresponding flow rate change in the other fluid; the flow controls can be individually misadjusted in the field any time by anybody; and the flow controls do not stay in proper adjustment over an extended period of time.
Attempts have been made to solve these problems by linking the syrup and diluent flow rates together. However, none of these valves have been completely successful to date. Three types of "linked" valves which have not proven to be completely successful are described below.
A first type of linked valve is one which monitors syrup and soda flow with flow meters and controls the flow in the respective supply conduits with pulsating solenoids. This type of valve has proven to be too complex, too expensive, and often unreliable.
A second type of linked valve uses reciprocating pistons linked together to control syrup and soda flow. This type of valve has difficulty in achieving a high flow rate in a small package; produces casual drink temperatures which are too high; and has problems with the seals that separate the syrup and the soda chambers.
A third type of linked valve includes rotary volumetric pumping chambers mechanically linked with a common shaft. This type of valve experiences problems with fluid slippage through the device and with the seals that separate the syrup and soda chambers of the respective pumping chambers.
Accordingly, there is a need in the an for an improved apparatus for supplying metered volumes of concentrate and diluent in controlled proportions to the mixing station of a post-mix beverage dispenser.